Heavy-mineral analyses show that the main supply of sand for the beaches and sea floor off Southern California is provided directly by the adjacent land areas. The longshore movement of sand is only of local importance because obstacles along the coast, such as submarine canyons and points of land, limit the longshore movement of sand to small segments along the coast. A close examination of a coastal segment shows marked differences between Recent marine and nonmarine sediments, and suggests that longshore drift of sand within a segment is prominent. The concept of time, as used in correlation of heavy-mineral samples, should include consideration of source rocks and drainage patterns, and should not be based solely on depositional features.

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